U.S. Pat. No. 4,964,069, assigned to the assignee herein, describes a discharge device in which a pump cylinder and a resilient stop constructed in the manner of a snap locking mechanism. Before a partial stroke can be effected, it is necessary for the operator to apply a specific actuating pressure, so that after overcoming this pressure threshold, a liquid is discharged with a specific minimum force and speed. This construction ensures that an adequate pressure exists at the outset for atomizing the medium, and that the pump is actuated up to the end of its stroke. Consequently, the complete content of the medium reservoir or store, which simultaneously forms the pump cylinder, is discharged in one or two strokes. Such single or multiple dosing devices are important for the delivery of medicaments, which are particularly critical with respect to the dosage, contamination, conservation or other criteria.
Published PCT application No. WO 92/00812, assigned to the assignee herein, discloses the use of medium reservoirs for a single discharge stroke, which are closed by a stopper simultaneously serving as a piston, the stopper being perforated by a needle for actuation purposes.
FR-A-1 535 293 discloses a tamper preventer for aerosol valves, in which predetermined breaking points are provided between the cap carrying the nozzle and a flange-like bead which can be snapped onto the container closure cover. These breaking points break prior to the first use.
EP-B-521 022 discloses a two-compartment atomizer, in which the stroke of a thrust piston pump is limited by a rocker on the circumference of the casing which is advanced for a second stroke.
DE-U-29 601 047 discloses a pump atomizer, which is designed for two successive discharge strokes. For this purpose on the sleeve receiving the medium container forming the pump cylinder there are two predetermined breaking rings, which come into successive engagement.
The second predetermined breaking ring forms a stop for ending the first discharge stroke step.